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31-May-2011, 8:56 PM
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#1
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Junior Member
Join Date: May 2011
Posts: 26
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Reception Problems
I'd like some advice about potential solutions to weak or intermittent TV reception. I have a standard multi-band rooftop antenna (about 10 years old) pointed south to southeast, supposedly the direction of most of the broadcasters in the area. I have messed with the direction somewhat with no signal improvement. The antenna is connected to some kind of amp that is then split into cables going throughout the house to two TVs and an empty jack.
According to the chart below, i should have great reception. I never had a complaint about the analog signal but have experienced intermittent lost signals and pixelation in the digital era. The typical signal at the TVs are 25 to 32 db with the amp and 22 or less (no signal) without the amp. I was thinking of trying a new antenna but am not convinced this would help. However, I am open to suggestions before i call the cable company.
http://www.tvfool.com/?option=com_wr...21930b794fcc85
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31-May-2011, 9:51 PM
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#2
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Moderator
Join Date: Oct 2010
Location: Greater Seattle Area
Posts: 4,773
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Which of these two antennas looks most like yours?
VHF/FM
UHF/VHF
Have you tried removing the amplifier completely? The signal levels in your area are strong enough to advise against any amplifier. Certainly when only two sets are connected.
Have you inspected the antenna for corrosion and other wear?
__________________
If the well is dry and you don't see rain on the horizon, you'll need to dig the hole deeper. (If the antenna can't get the job done, an amp won't fix it.)
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31-May-2011, 10:57 PM
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#3
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Senior Member
Join Date: Jun 2010
Posts: 2,697
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TV Antennas and Reception
The Tv stations transmissions at your location are Very Strong. So there is problems with the distribution system. Check ALL Connections , look inside the connectors on the ends of the coax and see if the outer foil shield / shield wires are pushed in toward the center conductor wire , the center conductor wire is wire that carries the signal. Also look and see if metal shavings/flakes are on the foam that is in between the center wire and the outer metal foil shield and shield wires. I recommend removing ALL amplifiers parts , the power supply , any power injectors , any and all amplifiers. I recommend connecting a known to be good coax from a known to be good matching transformer at the antenna and a known to be good antenna - connected direct to one Tv. Point the outside Tv antenna at about 150 degrees magnetic compass , here is how to point Tv antennas , http://www.kyes.com/antenna/pointing/pointing.html . Only use a 2 way splitter for the two Tv's in the house , do not use a 3 way splitter , 4 way splitter or more splitters , every time a split takes place the signal is reduced.
Last edited by John Candle; 31-May-2011 at 11:29 PM.
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31-May-2011, 11:01 PM
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#4
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Junior Member
Join Date: May 2011
Posts: 26
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My antenna looks like the UHF/VHF antenna.
Barely any usable signal to the TV at all without the amp. The typical signal at the TVs are 25 to 32 db with the amp and 22 or less (no signal) without the amp.
The antenna looks fine physically. It has the usual oxidation you'd expect for something aluminum sitting out in the elements for 10 years.
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31-May-2011, 11:02 PM
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#5
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Senior Member
Join Date: Jun 2010
Posts: 2,697
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TV Antennas and Reception
To Prove that Digital Broadcast Tv Transmissions are Strong at your location , use one of these NON Amplified indoor Tv antennas connected to one Tv , http://forum.tvfool.com/showthread.php?t=233 . Here is how to point indoor Tv antennas , http://www.kyes.com/antenna/pointing/pointing.html . radio shack also has a simple NON Amplified indoor tv antenna , catalog number 15-1874
Last edited by John Candle; 31-May-2011 at 11:35 PM.
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31-May-2011, 11:08 PM
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#6
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Junior Member
Join Date: May 2011
Posts: 26
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John,
What is the matching transformer and what does it do?
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31-May-2011, 11:17 PM
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#7
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Senior Member
Join Date: Jun 2010
Posts: 2,697
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TV Antennas and Reception
A matching transformer connects the coax to the outside roof top type Tv antenna. It matches the 300 ohm connection points of the tv antenna to the 75 ohm coax. The radio shack catalog number 15-1230 is a typical matching transformer
Last edited by John Candle; 31-May-2011 at 11:23 PM.
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31-May-2011, 11:33 PM
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#8
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Senior Member
Join Date: Jun 2010
Posts: 2,697
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TV Antennas and Reception
Read and understand about , REAL Digital Broadcast Tv Channels , Virtual Digital Broadcast Tv Channels , Analog Broadcast Tv Channels , http://forum.tvfool.com/showthread.php?t=695
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1-Jun-2011, 2:32 AM
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#9
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Moderator
Join Date: Oct 2010
Location: Greater Seattle Area
Posts: 4,773
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This Manual illustrates the location of, and how to connect the matching transformer. Notice the illustration at the end of step 3. If you find that you can not loosen the hardware to disconnect the matching transformer wires from the lead in terminals (illustrated at the end of step 1), you should consider replacing the antenna.
If water has entered the coax cable, it needs to be replaced.
__________________
If the well is dry and you don't see rain on the horizon, you'll need to dig the hole deeper. (If the antenna can't get the job done, an amp won't fix it.)
(Please direct account activation inquiries to 'admin')
Last edited by GroundUrMast; 1-Jun-2011 at 2:35 AM.
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1-Jun-2011, 2:32 AM
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#10
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Junior Member
Join Date: May 2011
Posts: 26
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Thanks John. Since it seems that you do not think that the antenna itself is the problem, this transformer and the cabling to and from it are the first place to investigate. I have already tested the distribution system with and without the amp and its cabling and the results were the same for both TVs. I doubt that the cabling to both TVs have failed in the same way at the same time; so, I will not rewire the house unless I am convinced it is necessary.
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1-Jun-2011, 2:34 AM
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#11
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Moderator
Join Date: Oct 2010
Location: Greater Seattle Area
Posts: 4,773
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The most likely components to fail will be in the weather.
__________________
If the well is dry and you don't see rain on the horizon, you'll need to dig the hole deeper. (If the antenna can't get the job done, an amp won't fix it.)
(Please direct account activation inquiries to 'admin')
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1-Jun-2011, 2:42 AM
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#12
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Junior Member
Join Date: May 2011
Posts: 26
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Thanks GUM. There is some kind of black box attached to the mast that must be the transformer as coax cable from the house enters and the two wire cable exits and is attached to the antenna. I'll mess with that first and see what happens. Looks like the least expensive option for swapping out parts.
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1-Jun-2011, 2:53 AM
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#13
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Moderator
Join Date: Oct 2010
Location: Greater Seattle Area
Posts: 4,773
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Quote:
Originally Posted by jc5000
Thanks GUM. There is some kind of black box attached to the mast that must be the transformer as coax cable from the house enters and the two wire cable exits and is attached to the antenna. I'll mess with that first and see what happens. Looks like the least expensive option for swapping out parts.
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That sounds like the actual amplifier. - Example -The indoor power supply and power insertion block is often mistaken for the amplifier. You may find that once ALL the amplifier components are removed your reception may dramatically improve... here's hoping anyway...
There are some older matching transformers that could look like that though.
__________________
If the well is dry and you don't see rain on the horizon, you'll need to dig the hole deeper. (If the antenna can't get the job done, an amp won't fix it.)
(Please direct account activation inquiries to 'admin')
Last edited by GroundUrMast; 1-Jun-2011 at 5:10 AM.
Reason: Added image
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1-Jun-2011, 8:01 AM
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#14
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Senior Member
Join Date: Jun 2010
Posts: 2,697
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TV Antennas and Reception
I am not suggesting replacing all of the cable in the house. If the outdoor antenna has a black box as part of the antenna , and the coax is connected to it then the antenna may have a built in/on matching transformer and that matching transformer may be bad. A good matching transformer and a long length of cable connected to one Tv will show that the reception of the antenna is good. And the long length of coax can be used to trouble shoot the distribution system by connecting at different points of the distribution system so as to find the part of the system that needs to be fixed.
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1-Jun-2011, 9:03 AM
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#15
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Senior Member
Join Date: Jun 2010
Posts: 2,697
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TV Antennas and Reception
Here is a example picture and information , terminal board/matching transformer that snaps into place on the underside of the antenna . Winegard CB 1469 . http://winegarddirect.com
Last edited by John Candle; 1-Jun-2011 at 9:08 AM.
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1-Jun-2011, 8:59 PM
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#16
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Junior Member
Join Date: May 2011
Posts: 26
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GUM, This picture you embedded looks exactly like the setup I have. I guess this pre-amp is also the transformer because coax cable goes into the black box from the house but the two-wire cable comes out of the box to the antenna connections. Then there is another powered box inside the house that receives the coax from the black box. It is distributed from there to the TVs thru additional coax cable.
Quote:
Originally Posted by GroundUrMast
That sounds like the actual amplifier. - Example -The indoor power supply and power insertion block is often mistaken for the amplifier. You may find that once ALL the amplifier components are removed your reception may dramatically improve... here's hoping anyway...
There are some older matching transformers that could look like that though. |
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1-Jun-2011, 9:49 PM
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#17
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Moderator
Join Date: Oct 2010
Location: Greater Seattle Area
Posts: 4,773
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There are several variations of this concept... Generally, the part(s) inside the building are power related, and are designed to send power up to the mast mounted amplifier unit.
The mast mounted unit may have one or two inputs. If two, one is usually for VHF and the other for UHF. There can be any combination of 300 ohm twin-lead or 75 ohm coax input and output. It sounds like you may have a short section of 300 ohm twin-lead from the antenna to the amplifier and the output is 75 ohm coax.
I would be very curious to know how your system performs when you remove the amp and power supply. If there is a short section of twin-lead between the antenna and amp now, a matching transformer will be needed.
__________________
If the well is dry and you don't see rain on the horizon, you'll need to dig the hole deeper. (If the antenna can't get the job done, an amp won't fix it.)
(Please direct account activation inquiries to 'admin')
Last edited by GroundUrMast; 1-Jun-2011 at 9:59 PM.
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1-Jun-2011, 10:13 PM
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#18
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Junior Member
Join Date: May 2011
Posts: 26
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Ok, my next experiment will be to remove both the outdoor pre-amp/transformer piece and the indoor power supply piece. Previously, I experimented by removing just the power supply piece on the inside of the house and the signal was much worse. I will report on the outcome.
Quote:
Originally Posted by GroundUrMast
There are several variations of this concept... Generally, the part(s) inside the building are power related, and are designed to send power up to the mast mounted amplifier unit.
The mast mounted unit may have one or two inputs. If two, one is usually for VHF and the other for UHF. There can be any combination of 300 ohm twin-lead or 75 ohm coax input and output. It sounds like you may have a short section of 300 ohm twin-lead from the antenna to the amplifier and the output is 75 ohm coax.
I would be very curious to know how your system performs when you remove the amp and power supply. If there is a short section of twin-lead between the antenna and amp now, a matching transformer will be needed.
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11-Jun-2011, 12:52 AM
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#19
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Junior Member
Join Date: May 2011
Posts: 26
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I finally went up on the roof again and into the attic to satisfy our curiosity. Similar to the diagram that you provided: THere was a transformer right at the antenna contacts; this was connected to a coax cable hooked on the other end to another transformer that went in the opposite direction into the pre-amp/transformer (evidently the pre-amp/transformer two wire cable was not long enough to reach the antenna contacts); then the cable from the pre-amp/transformer went into a powered box inside the attic; the signal from the powered box went to a four way splitter that had cabling to the two TV's and an unused jack.
So, I disconnected everything as directed. I bought a new transformer at the Shack and hooked it directly to the antenna contacts. The cable from the new transformer goes directly to the 4-way splitter in the attic now.
The results are that my reception and signals at the TVs are pretty much the way they were before with the pre-amp, which is kind of interesting. I guess the pre-amp was not doing a whole lot. I repositioned the antenna while I was up there and most stations are acceptable at around 30db. The worst stations are local channel 2 (24 db) and local channels 39-1, 39-2 (variable at 12-18db); so the latter fades repeatedly.
Another hardware item I noted is that one of the long horizontal spokes on the side of the antenna facing away from the transmitters is missing. I am not sure how big an impact this has as it is a fairly large antenna.
Quote:
Originally Posted by GroundUrMast
There are several variations of this concept... Generally, the part(s) inside the building are power related, and are designed to send power up to the mast mounted amplifier unit.
The mast mounted unit may have one or two inputs. If two, one is usually for VHF and the other for UHF. There can be any combination of 300 ohm twin-lead or 75 ohm coax input and output. It sounds like you may have a short section of 300 ohm twin-lead from the antenna to the amplifier and the output is 75 ohm coax.
I would be very curious to know how your system performs when you remove the amp and power supply. If there is a short section of twin-lead between the antenna and amp now, a matching transformer will be needed.
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11-Jun-2011, 1:12 AM
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#20
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Moderator
Join Date: Oct 2010
Location: Greater Seattle Area
Posts: 4,773
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I presume you are referring to KPRC (NBC, real channel 35, virtual channel 2.X) and KIAH (CW, real channel 38, virtual channel 39.X).
Is reception of KIAH stable or does it break-up?
Can you afford to buy a 'test' cable? I would be curious to know how the system performs when you connect the antenna to only the TV you are using as your signal meter. The goal is to determine with some certainty, the quality of the signal from the antenna and to remove (while testing) the possible problems in your distribution network.
Are all of the 4-way splitter ports connected to sets or 'capped' with terminating resistors?
Broken, bent or missing elements are not going to improve the antennas performance. However, if only one of the longest elements is missing, I doubt the effect on the UHF channels will be much. In your area everyone is using high-VHF or UHF channels, K04QT is an exception but rabbitears.com indicates it is not on the air and you would need to use a rotator or separate antenna to get it anyway.
If you have been able to loosen the hardware to replace the matching transformer, I'm inclined to hold off from recommending replacement of the antenna... for now.
__________________
If the well is dry and you don't see rain on the horizon, you'll need to dig the hole deeper. (If the antenna can't get the job done, an amp won't fix it.)
(Please direct account activation inquiries to 'admin')
Last edited by GroundUrMast; 11-Jun-2011 at 1:24 AM.
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